In systems for recovering refrigerant from refrigeration equipment under service, there have been a number of techniques proposed for removing or purging air from the recovered refrigerant. For example, in a system in which the refrigerant is pumped to a storage container by a compressor or liquid refrigerant pump, an air purge chamber may be connected between the refrigerant compressor or pump and the storage container for accumulating refrigerant in liquid phase at a lower portion of the chamber, and trapping air and other non-condensibles over the liquid refrigerant at the upper portion of the chamber. The trapped air and non-condensibles may be automatically or manually purged through a suitable valve when pressure becomes excessive.
It is a general object of the present invention to provide a refrigerant handling system and method, particularly a refrigerant recovery system and method, of the described character in which the air purge chamber outlet includes facility for isolating the outlet from the vapor space over the refrigerant, and thereby preventing inadvertent removal of non-condensibles with the liquid refrigerant. Another object of the present invention is to provide a refrigerant handling system of the described character that includes facility for clearing refrigerant from the handling system components, including the air purge chamber, preparatory to service on the system or employing the system in conjunction with a different refrigerant, and thereby preventing venting of the refrigerant to the atmosphere and inadvertent mixing and contamination of different types of refrigerant.
A refrigerant handling system in accordance with a presently preferred embodiments of the invention includes an air purge chamber and a refrigerant pump for directing refrigerant into the air purge chamber so that the refrigerant collects in liquid phase at a lower portion of the chamber while air and other non-condensibles collect in a vapor space at the upper portion of the chamber over the refrigerant. A purge valve is connected to the upper portion of the chamber for automatically or manually purging air and other non-condensibles from the chamber. A refrigerant outlet is positioned at the lower portion of the chamber for drawing liquid phase refrigerant from the chamber while maintaining a seal of liquid phase refrigerant at the outlet within the chamber isolating the outlet from the vapor space, and preventing removal of air and other non-condensibles from the chamber through the outlet. Preferably, this liquid seal is maintained by maintaining a minimum level of liquid phase refrigerant in the lower portion of the chamber at the outlet.
In the preferred embodiments of the invention, the refrigerant pump mechanism comprises a compressor connected through a condenser to the air purge chamber, so that the condenser at least partially condenses refrigerant prior to entry into the air purge chamber. The air purge chamber inlet from the compressor is positioned at a level above the minimum refrigerant level with the chamber that maintains the liquid seal at the chamber outlet. A check valve is connected at one end either to the liquid refrigerant outlet from the air purge chamber or to a separate outlet, and at a second end between the condenser and the chamber inlet. Both the air purge chamber and the condenser may be cleared of refrigerant by connection to the condenser between the compressor and the condenser, and drawing refrigerant from the condenser and from the air purge chamber through the check valve and the condenser. In various embodiments of the invention, minimum liquid refrigerant level is maintained in the air purge chamber by a liquid refrigerant level sensor and a solenoid valve, and by a standpipe at the refrigerant outlet with an open end covered by a baffle .